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參數(shù)資料
| 型號(hào)： | M74HC4538B1R |
| 廠商： | STMICROELECTRONICS |
| 元件分類(lèi)： | 諧振器 |
| 英文描述： | HC/UH SERIES, DUAL MONOSTABLE MULTIVIBRATOR, PDIP16 |
| 封裝： | DIP-16 |
| 文件頁(yè)數(shù)： | 14/18頁(yè) |
| 文件大小： | 587K |
| 代理商： | M74HC4538B1R |
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M74HC4538
Functional description
5/18
2
Functional description
Standby state
The external capacitor Cx, is fully charged to VCC in the standby state. Hence, before
triggering, transistor Qp and Qn (connected to the Rx/Cx node) are both turned-off. The two
comparators that control the timing and the two reference voltage sources stop operating.
The total supply current is therefore only leakage current.
Trigger operation
Triggering occurs when:
–
A is low and B has a falling edge
–
B is high and A has a rising edge
After the multivibrator has been retriggered, the comparator C1 and C2 start operating and
Qn is turned on. Cx then discharges through Qn. The voltage at the node Rx/Cx external
falls.
When it reaches VREFL the output of comparator C1 becomes low. This in turn resets the
flip-flop and Qn is turned off.
At this point C1 stops functioning but C2 continues to operate.
The voltage at R/C external begins to rise with a time constant set by the external
components Rx and Cx.
Triggering the multivibrator causes Q to go high after internal delay due to the flip-flop and
the gate. Q remains high until the voltage at R/C external rises again to VREFH . At this point
C2 output goes low and G goes low. C2 stops operating. That means that after triggering
when the voltage R/C external returns to VREFH the multivibrator has returned to its
monostable state. In the case where Rx Cx are large enough and the discharge time of the
capacitor and the delay time in the IC can be ignored, the width of the output pulse tw(out) is
as follows:
Re-triggered operation
When a second triggered pulse follows the first, its effect will depend on the state of the
multivibrator. If the capacitor Cx is being charged, the voltage level of Rx/Cx external falls to
VREFL again and Q remains high i.e. the retrigger pulse arrives in a time shorter than the
period Rx Cx seconds, the capacitor charging time constant. If the second trigger pulse is
very close to the initial trigger pulse it is ineffective; i.e. the second trigger must arrive in the
capacitor discharge cycle to be ineffective; hence the minimum time for a second trigger to
be effective, trr (min.) depends on VCC and Cx.
Reset operation
CD is normally high. If CD is low, the trigger is not effective because Q output goes low and
trigger control flip-flop is reset. Also transistor Op is turned on and Cx is charged quickly to
VCC. Then, if CD input goes low the IC becomes waiting state both in operating and non
operating state.
Rx
Cx
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.
0
=
t
)
OUT
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| M74HC4538C1R | 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:DUAL RETRIGGERABLE MONOSTABLE MULTIVIBRATOR |
| M74HC4538M1R | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Mono Multivib RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類(lèi)型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時(shí)間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| M74HC4538RM13TR | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Mono Multivib RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類(lèi)型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時(shí)間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| M74HC4538RM13TR | 制造商:STMicroelectronics 功能描述:Dual Retriggerable Monostable Multivibra |
| M74HC4538TTR | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Mono Multivib RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類(lèi)型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時(shí)間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
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